Accurately estimating the prevalence of autism spectrum disorders (ASD) in early childhood is particularly challenging because many children are not diagnosed until school age. The major aim of this project is to estimate the prevalence of ASD in a prospective sample of children using a two-stage screening and referral process developed by the FIRST WORDS(r) Project. Children will be recruited from a general population sample of over 6,000 children who were screened with a broadband parent-report surveillance checklist between 6 and 24 months of age. An autism-specific interactive screening tool was videotaped on selected children. To date, we have identified 42 children from this prospective sample who were diagnosed with ASD at 3 years of age or older; 40 received a positive broadband screen and 41 a positive autism-specific screen. In order to estimate how many children with ASD may have been missed from this prospective sample, families of all children who completed the broadband screener will be mailed a brief follow-up questionnaire to inquire whether their child has been diagnosed with ASD or another developmental disability, is receiving special education services, or the parents are concerned that their child may have a developmental problem. Children flagged from this questionnaire will be invited for a diagnostic evaluation to confirm or rule out ASD. The following research objectives will be addressed: 1) to calculate sensitivity, specificity, positive predictive value, and negative predictive value for the broadband and autism-specific screening tools; 2) to compare the autism-specific interactive screening tool with a newly developed autism-specific parent-report screening tool on a subset of this sample; and 3) to estimate the prevalence of autism and the broader ASD and describe demographic and developmental characteristics of this prospective sample, which includes about 1/4th the birth rate of a small urban and surrounding rural communities. Focus groups will be conducted with parents and professionals to seek input on how to improve the screening process and offer better ways to share information about initial diagnosis and access to services. The expected outcomes of this study will: 1) document the effectiveness of a community-based screening model to estimate the prevalence of ASD in early childhood; and 2) offer methods and materials to support families and professionals participating in an ASD surveillance system and to increase community and public health awareness of ASD. [unreadable] [unreadable] [unreadable]